Ron Rosenfeld wrote...
....
Didn't you also point out that the problem is the parser, and that equations
with more than seven nested functions that were created in other programs would
work OK in Excel?

Whether Excel's formula parser is the problem is speculation. However,
OpenOffice accepts the OP's original formula (once commas are changed
to semicolons), and gives the intended result. If the file were saved
in XLS format, Excel has no problem opening the file and
using/recalculating the formula as-is. Excel just can't edit it.

So, yes, the OP could install OpenOffice and use it to create deeply
nested formulas, save as XLS, then use (but not edit) in Excel.